Camera with frame shift prevention during exposure

ABSTRACT

A camera comprising a main body part with spaced film supply and film take-up chambers and an exposure opening located between the film supply and take-up chambers and configured for exposing an unexposed film frame, a metering pawl for engaging a film perforation during exposure of the film frame at the exposure opening, and a film winding take-up for moving an exposed frame in a film take-up direction from the exposure opening to the film take-up chamber, is characterized in that the metering pawl is supported to engage a film perforation between the exposure opening and the film supply chamber during exposure of a film frame at the exposure opening, and a tensioning spring urges the metering pawl substantially opposite to the film take-up direction in order to tension a film frame at the exposure opening. Since the film length between the metering pawl and the film winding take-up is longitudinally tensioned, the film frame is similarly tensioned at the exposure opening. Thus, the film tensioning positively acts to prevent frame shift during exposure of the film frame.

CROSS-REFERENCE TO RELATED APPLICATION

Reference is made to commonly assigned, application Ser No. 09/283,719,entitled METERING/RE-COCKING MEMBER FOR ENGAGING FILM DURING EXPOSUREAND FOR RE-COCKING SHUTTER ACTUATOR, SEPARATES FROM SHUTTER ACTUATORWHEN RE-COCKED and filed Apr. 1, 1999 in the name of Anthony DiRisio,now U.S. Pat. No. 6,092,936.

FIELD OF THE INVENTION

The invention relates generally to the field of photography, and inparticular to cameras. More specifically, the invention relates to acamera with a film metering pawl that engages a filmstrip at a filmperforation to prevent frame shift during exposure of a film frame.

BACKGROUND OF THE INVENTION

It is generally known for a camera to have a main body part with spacedfilm supply and film take-up chambers. An exposure opening is locatedbetween the film supply and take-up chambers and is configured forexposing successive film frames. A metering or sensing pawl is supportedfor engaging a film perforation during exposure of the film frame at theexposure opening. A film winding take-up is operated to move eachexposed frame from the exposure opening to the film take-up chamber andto advance a fresh frame from the film supply chamber to the exposureopening. When the film metering pawl engages the film perforation, it isintended to prevent frame shift. The reason for this is that it isnecessary to keep the film frame stationary during exposure.

Prior art U.S. Pat. No. 3,999,199 issued Dec. 21, 1976 discloses acamera in which a metering or sensing pawl is supported to engage a filmperforation between the exposure opening and the film winding take-upduring exposure of a film frame at the exposure opening. A compressionspring urges the metering pawl opposite to the film take-up directionand towards the exposure opening, and therefore fails to tension thefilm frame at the exposure opening. Consequently, it is not clearwhether frame shift during exposure may occur.

Prior art U.S. Pat. No. 5,708,888 issued Jan. 13, 1998 discloses acamera in which a cantilever beam has one end anchored to a filmpressure plate and another end that is intended to engage a filmperforation to prevent frame shift during exposure of a film frame.Presumably, a metering pawl or the equivalent is provided in addition tothe cantilever beam.

--The Cross-Referenced Application--

The cross-referenced application discloses a camera including a shutterblade supported to move open to expose a frame on a filmstrip, a shutteractuator supported for movement to move the shutter blade open and formovement to be re-cocked, an actuating spring for urging the shutteractuator to move the shutter blade open, and a metering/re-cockingmember having a metering pawl for engaging the filmstrip at aperforation during exposure of the frame. The metering/re-cocking memberhas a re-cocking portion and is supported for movement to move there-cocking portion against the shutter actuator to move the shutteractuator to be re-cocked. A film tensioning spring urges themetering/re-cocking member, when the metering pawl engages the filmstripat a perforation, to prevent the frame being exposed from shiftingduring exposure. The shutter actuator is supported for movement to bespaced from the metering/re-cocking member, when the shutter actuator isre-cocked, to prevent the actuating spring from exerting any influenceon the metering pawl when the frame is exposed.

SUMMARY OF THE INVENTION

A camera comprising a main body part with spaced film supply and filmtake-up chambers and an exposure opening located between the film supplyand take-up chambers and configured for exposing an unexposed filmframe, a metering pawl for engaging a film perforation during exposureof the film frame at the exposure opening, and a film winding take-upfor moving an exposed frame in a film take-up direction from theexposure opening to the film take-up chamber, is characterized in that:

the metering pawl is supported to engage a film perforation between theexposure opening and the film supply chamber during exposure of a filmframe at the exposure opening; and

a tensioning spring urges the metering pawl substantially opposite tothe film take-up direction in order to tension a film frame at theexposure opening.

Since the film length between the metering pawl and the film windingtake-up is longitudinally tensioned, the film frame is similarlytensioned at the exposure opening. Thus, the film tensioning positivelyacts to prevent frame shift during exposure of the film frame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front exploded perspective view of a camera according to apreferred embodiment of the invention;

FIG. 2 is a rear perspective view of the camera;

FIG. 3 is a partial-section, plan view of the camera with certainportions removed to facilitate illustration;

FIG. 4 is a front elevation view of the camera with certain portionsremoved to facilitate illustration;

FIG. 5 is similar to FIG. 3, but is depicted when a shutter releasebutton is manually depressed to initiate making an exposure;

FIG. 6 is similar to FIG. 4, but corresponds in operation to FIG. 5;

FIG. 7 is a continuation of operation from FIG. 5;

FIG. 8 corresponds in operation to FIG. 7;

FIG. 9 is a continuation of operation from FIG. 7;

FIG. 10 corresponds in operation to FIG. 9;

FIG. 11 corresponds in operation to FIG. 9;

FIG. 12 is a continuation of operation from FIG. 11;

FIG. 13 is a continuation of operation from FIG. 12;

FIG. 14 is a continuation of operation from FIG. 10;

FIG. 15 is a continuation of operation from FIG. 14;

FIG. 16 is a continuation of operation from FIG. 15;

FIG. 17 is a continuation of operation from FIG. 16;

FIG. 18 is a continuation of operation from FIG. 17;

FIG. 19 is a continuation of operation from FIG. 18;

FIG. 20 is a continuation of operation from FIG. 19;

FIG. 21 is a continuation of operation from FIG. 20; and

FIG. 22 is a top perspective view of a support piece, shown from its topin FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The invention is disclosed as being embodied preferably in a relativelysimple inexpensive camera such as a one-time-use camera. Because thefeatures of a one-time-use camera are generally known, the descriptionwhich follows is directed in particular only to those elements formingpart of or cooperating directly with the disclosed embodiment. It is tobe understood, however, that other elements may take various forms knownto a person of ordinary skill in the art.

Referring now to the drawings, FIGS. 1-22 partially show a one-time-usecamera 10.

The one-time-use camera 10 is a simple point-and-shoot camera thatincludes an opaque plastic main body part 12 shown in FIGS. 1 and 2. Themain body part 12 has a rearwardly-open film take-up chamber 14 thatcontains a conventional film cartridge 16, a rearwardly-open film supplychamber 18 that contains an unexposed filmstrip 20 which is prewoundduring camera manufacture from the film cartridge into an unexposed filmroll 22 in the film supply chamber, and a rearwardly-open exposureopening 24 that is behind a front aperture 26 in the main body part.Ambient light passes through the front aperture 26 to the exposureopening 24 in order to expose successive frames 28 of the filmstrip 20.A pair of opaque plastic front and rear cover parts (not shown) housethe main body part 12 between them.

A film winding thumbwheel 30 is rotatably engaged with a film spoolinside the film cartridge 16 in the film take-up chamber 14. The filmwinding thumbwheel 30 is manually rotated in a circular film windingdirection 32, i.e. counter-clockwise in FIGS. 1 and 2, to wind eachframe 28 of the filmstrip 20 that is exposed at the exposure opening 24into the film cartridge and to advance a fresh frame of the filmstripfrom the unexposed film roll 22 to the exposure opening. As indicated inFIGS. 2 and 3, the filmstrip 20 is incrementally moved in asubstantially linear film take-up direction 34 from the film supplychamber 18, across the exposure opening 24, to the film take-up chamber14.

A fixed-focus taking lens 36 is held between a lens plate 38 and a lensretainer 39 which are connected together. The lens plate 38 is connectedto the main body part 12 to position the taking lens 36 over the frontaperture 26.

A fixed pivot pin 40 on a support piece 42 which is fitted to the mainbody part 12 projects into a straight or slightly curved slot 44 in ashutter blade 46 to support the shutter blade for translation andpivoting. See FIG. 1. The shutter blade 46 is pivoted open clockwise inFIGS. 8 and 11 and against a limit stop 48 on the main body part 12 touncover the front aperture 26 in order to permit ambient light to passfrom the taking lens 36, through the front aperture, to the exposureopening 24 and is pivoted closed counter-clockwise in FIGS. 12 and 13 tore-cover the front aperture. A closing spring 50 biases the shutterblade 46 to be pivoted closed to re-cover the front aperture 26. Alight-intercepting rib 52 on the main body part 12 partially surroundsthe shutter blade 46 when the shutter blade is closed as shown in FIG.4, and it has a blade stop end 54 against which the closing spring 50urges the shutter blade.

A shutter actuator 56 has a bottom rear guide pin 58 that is confined tomovement within a straight top slot 60 in the support piece 42, a bottomfront guide pin 62 that is confined to movement around an elongateisland 64 within a top cavity 66 in the support piece, and an actuatingstriker 68 that protrudes outwardly from a straight front slot 70 in thesupport piece. See FIGS. 1, 3, 4 and 22. A helical tension spring 72spring biases the shutter actuator 56 substantially to the right inFIGS. 1 and 3 to advance the actuating striker 68 first against a tang74 on the shutter blade 46, and then over the tang, to pivot the shutterblade open to uncover the front aperture 26. See FIGS. 6, 8 and 11.

A locking member 76 is supported for pivotal movement about a fixedpivot pin 78 on the support piece 42. The locking member 76 has anactuator lock or catch 80 that engages the shutter actuator 56 at anupstanding post 82 on the shutter actuator to prevent the shutteractuator from being moved substantially to the right in FIGS. 1 and 3via the helical tension spring 72, and it has a rigid thumbwheel lock orpawl 84 that engages any one of a continuous array of peripheral teeth86 on the film winding thumbwheel 30 to prevent the film windingthumbwheel from being manually rotated in the film winding direction 32.A return spring 88 urges the locking member 76 to pivot clockwise inFIGS. 1 and 3 for the actuator lock 80 to engage the upstanding post 82on the shutter actuator 56 and for the thumbwheel lock 84 to engage anyone of the peripheral teeth 86 on the film winding thumbwheel 30.

A resilient flexible anti-backup pawl 90 on a top piece 92 which isconnected to the main body part 12 over the support piece 42 isinherently biased to engage any one of the peripheral teeth 88 on thefilm winding thumbwheel 30 to prevent reverse (unwinding) rotation ofthe film winding thumbwheel, i.e. rotation opposite to the film windingdirection 32. See FIGS. 1-3.

A shutter release button 94 on the top piece 92 is resilientlycantilevered to permit it to be manually depressed to take a picture.The shutter release button 94 has a depending projection 96 that isswung against an upstanding projection 98 on the locking member 76, whenthe shutter release button is manually depressed. This pivots thelocking member 76 counter-clockwise in FIGS. 1, 3 and 5, for theactuator lock 80 to disengage from the upstanding post 82 on the shutteractuator 56 and for the thumbwheel lock 84 to disengage from any one ofthe peripheral teeth 86 on the film winding thumbwheel 30.

A frame counter 100 for indicating the number of exposures remaining tobe made on the filmstrip 20 is supported for rotation on the top piece92. See FIG. 1. A direct see-through viewfinder 102 for viewing thesubject to be photographed is positioned on the top piece 102, beneaththe frame counter 100.

A metering/re-cocking member 104 is supported for movement between themain body part 12 and the support piece 42. The metering/re-cockingmember 104 has a film sensing pawl 106 and a film metering pawl 108 thatare adapted to engage the filmstrip 20 at successive pairs of filmperforations 110 and 112. The film sensing pawl 106 and the filmmetering pawl 108 are fixed with respect to one another on themetering/re-cocking member 104. A re-cocking projection 114 on themetering/re-cocking member 104 is confined to movement within a bent topslot 116 in the support piece 42 and is adapted to push against a frontedge 118 of the shutter actuator 56 to re-cock the shutter actuator,i.e. to return the shutter actuator to its original position shown inFIGS. 3 and 4, when each frame 28 of the filmstrip 20 that is exposed atthe exposure opening 24 is wound into the film cartridge 16 and a freshframe of the filmstrip is advanced from the unexposed film roll 22 tothe exposure opening. That is, each time the filmstrip is moved in thefilm take-up direction 34. See FIGS. 1-3 and 22. A helical tensionspring 120 biases the metering/re-cocking member 104 substantially tothe right in FIGS. 1 and 3 and to the left in FIG. 2.

A fixed blocking device 122 on the support piece 42 has an inclinedblocking edge 124 which is positioned within a predetermined blockingrange 126 of the shutter blade 46 to prevent the shutter blade fromunintentionally being moved open to uncover the front aperture 26 whenthe shutter blade is moved accidentally due to mechanical shock, such aswhen the one-time-use camera 10 is dropped or jarred. The blocking range126 is defined by a slight clearance space or gap 126 in FIG. 4 which isbetween the inclined blocking edge 122 and the shutter blade 46. Theclearance space 126 permits the shutter blade 46 to be pivoted open touncover the front aperture 26 when the shutter actuator 56 is moved topivot the shutter blade open (following manual depression of the shutterrelease button 94). See FIG. 6.

--Operation--

Beginning with FIGS. 1-5, when the shutter release button 94 is manuallydepressed to take a picture, its depending projection 96 is swungagainst the upstanding projection 98 on the locking member 76. Thispivots the locking member counter-clockwise in FIG. 5, for the actuatorlock 80 to disengage from the upstanding post 82 on the shutter actuator56 and for the thumbwheel lock 84 to disengage from any one of theperipheral teeth 86 on the film winding thumbwheel 30.

The unexposed frame 28 of the filmstrip 20 which is at the exposureopening 24 is held steady over the exposure opening to prevent any frameshift, because the anti-backup pawl 90 is engaging one of the peripheralteeth 86 on the film winding thumbwheel 30 to prevent reverse(unwinding) rotation of the thumbwheel and the tension spring 120 urgesthe metering pawl 108 in the film perforation 112 substantially oppositeto the film take-up direction 34. Thus, the film frame 28 islongitudinally tensioned across the exposure opening 24 and any frameshift is precluded.

Next, in FIGS. 5 and 6, the tension spring 72 moves the shutter actuator56 initially to the right to advance the actuating striker 68 forwardalong the slot 70 in the support piece 42 to against the tang 74 on theshutter blade 46. The shutter blade 46 is translated slightly to theright in FIG. 6 to change from a first closed end 128 of the slot 44 inthe shutter blade being against the pivot pin 40 to a second closed end130 of the slot being against the pivot pin. This moves the shutterblade 46 out of the blocking range 126 of the inclined blocking edge124, as can be seen by comparing FIGS. 4 and 6. Also, the shutter blade46 is slightly pivoted clockwise in FIG. 6 to separate from the bladestop end 54 of the light-intercepting rib 52.

Then, in FIGS. 7-11, the tension spring 72 moves the shutter actuator 56further to the right to advance the actuating striker 68 forward alongthe slot 70 in the support piece 42 and over the tang 74 on the shutterblade 46. This causes the shutter blade 46 to be pivoted open clockwisein FIGS. 8 and 11 and against the limit stop 48, to uncover the frontaperture 26. The shutter blade 46 is pivoted open with the second closedend 130 of the slot 44 in the shutter blade being against the pivot pin40. Thus, the shutter blade 34 remains out of the blocking range 126 ofthe inclined blocking edge 124. See FIGS. 7 and 11.

By comparing FIGS. 3, 5, 7 and 9, it can be seen that the bottom rearguide pin 58 on the shutter actuator 56 moves forward within the slot 60in the support piece 42, and the bottom front guide pin 62 on theshutter actuator moves forward within the cavity 66 in the supportpiece. The rear guide pin 58 moves from one end 132 of the slot 60 inFIG. 3 to an opposite end 134 of the slot in FIG. 9. The front guide pin62 moves from one end 136 of the island 64 in the cavity 66 in FIG. 3,along a front side 138 of the island in FIGS. 5 and 7, and around anopposite end 140 of the island in FIG. 9. When the front guide pin 62 ismoved to the opposite end 140 of the island 64, the tension spring 72can pivot the shutter actuator 56 counter-clockwise in FIG. 9 to retractthe actuating striker 68 inwardly from the slot 70 in the support piece42. The actuating striker 68 is pivoted at its rear guide pin 58. Theactuating striker 68 must be retracted inwardly from the slot 70 to getout of the way of the tang 74 when the shutter blade 46 is pivotedclosed to re-cover the front aperture 26. Otherwise, the actuatingstriker 68 would block the tang 74 to prevent closing of the shutterblade 46. Alternatively, the actuating striker 68 can be beveled on itsunderside to not block the tang 74 during closing of the shutter blade46.

As shown in FIG. 10, the metering/re-cocking member 104 remains in thesame position as in FIG. 3, with the film sensing pawl 106 and the filmmetering pawl 108 engaging the filmstrip 20 at one pair of the filmperforations 110 and 112.

Next, in FIG. 12, the closing spring 50 pivots the shutter blade 46closed to re-cover the front aperture 26. This is possible because theactuating striker 68 has been retracted inwardly from the slot 70 to getout of the way of the tang 74. The shutter blade 46 is pivoted closedwith the second closed end 130 of the slot 44 in the shutter blade beingagainst the pivot pin 40 in FIG. 12.

In FIG. 13, the closing spring 50 pivots the shutter blade 46 slightlyfurther to the blade stop end 54 of the light-intercepting rib 52 andthen slightly about the blade stop end. This allows the closing spring50 to translate the shutter blade 46 slightly to the left in FIG. 13 tochange from the second closed end 130 of the slot 44 in the shutterblade being against the pivot pin 40 to the first closed end 128 of theslot being against the pivot pin. Then, as shown in FIG. 4, the shutterblade 46 is returned to within the blocking range 126 of the inclinedblocking edge 124.

After the picture is taken, and before what is shown in FIG. 14, theshutter release button 94 is manually released to end manual depressionof the shutter release button. Thus, the depending projection 96 wouldbe swung away from the upstanding projection 98 on the locking member76.

In FIG. 14, the film winding thumbwheel 30 is begun to be manuallyrotated in the film winding direction 32 in order to wind the frame 28of the filmstrip 20 that is exposed at the exposure opening 24 into thefilm cartridge 16 and to advance a fresh frame of the filmstrip from theunexposed film roll 22 to the exposure opening. Since the filmstrip 20is moved in the film take-up direction 34, the film perforation 110begins to separate from the film sensing pawl 106 of themetering/re-cocking member 104 as shown in FIG. 14. However, the filmmetering pawl 108 of the metering/re-cocking member 104 remains in thefilm perforation 112. Thus, the metering/re-cocking member 104 is movedslightly to the left in FIG. 14, stretching the tension spring 120. There-cocking projection 114 on the metering/re-cocking member 104 issimilarly moved within the bent top slot 116 in the support piece 42 asshown in FIG. 14.

In FIG. 15, the film winding thumbwheel 30 is further rotated in thefilm winding direction 32, and a follower 142 on the metering/re-cockingmember 104 moves along a fixed cam 144 on the support piece 42 to causethe metering/re-cocking member to move slightly to the left and downwardin FIG. 15, separating the film metering pawl 108 of themetering/re-cocking member 104 from the film perforation 112.Simultaneously, the re-cocking projection 114 on the metering/re-cockingmember 104 is similarly moved within the bent top slot 116 in thesupport piece 42 as shown in FIG. 15.

In FIGS. 16 and 17, the film winding thumbwheel 30 is further rotated inthe film winding direction 32, and the tension spring 120 returns themetering/re-cocking member 104 to the right to re-position the filmsensing and metering pawls 106 and 108 of the metering/re-cocking memberagainst the filmstrip 20. At this time, the film sensing and meteringpawls 106 and 108 tend to bear lightly against the filmstrip 20 due tothe urging of the tension spring 120.

In FIG. 18, the film winding thumbwheel 30 is further rotated in thefilm winding direction 32, and the film sensing and metering pawls 106and 108 of the metering/re-cocking member 104 drop into another (thenext) pair of the film perforations 110 and 112 to re-engage thefilmstrip 20. The metering/re-cocking member 104 is pivoted slightlycounter-clockwise in FIG. 18 about a fixed nub 146 on the support piece42.

In FIG. 19, the film winding thumbwheel 30 is further rotated in thefilm winding direction 32, which causes the metering/re-cocking member104 to again begin to move to the left (since the film sensing andmetering pawls 106 and 108 of the metering/re-cocking member 104 are nowin another pair of the film perforations 110 and 112). This moves there-cocking projection 114 on the metering/re-cocking member 104 againstthe front edge 118 of the shutter actuator 56 to begin to re-cock theshutter actuator, i.e. to begin to return the shutter actuator to itsoriginal position shown in FIGS. 3 and 4. The upstanding post 82 on theshutter actuator 56 bears against the actuator lock 80 on the lockingmember 76 to pivot the locking member slightly counter-clockwise in FIG.19, which serves to decrement the frame counter 100 by "1." The frontguide pin 62 on the shutter actuator 56 is moved from the end 140 of theisland 64 in the cavity 66 in the support piece 42 to along a rear side148 of the island. The actuating striker 68 therefore remains retractedinwardly from the slot 70 in the support piece 42. This allows theshutter actuator 56 to be re-cocked, i.e. returned to its originalposition shown in FIGS. 3 and 4, without the tang 74 on the shutterblade 46 obstructing the actuating striker 68.

In FIG. 20, the film winding thumbwheel 30 is further rotated in thefilm winding direction 32, and the metering/re-cocking member 104 isfurther moved to the left. Movement of the metering/re-cocking member104 further to the left in FIG. 20 causes the re-cocking projection 114on the metering/re-cocking member to push the front edge 118 of theshutter actuator 56 to continue to re-cock the shutter actuator, i.e. tocontinue to return the shutter actuator to its original position shownin FIGS. 3 and 4. Also, the front guide pin 62 on the shutter actuator56 is moved from the rear side 148 of the island 64 in the cavity 66 inthe support piece 42 to the end 136 of the island.

When the front guide pin 62 on the shutter actuator 56 is moved to theend 136 of the island 64 in the cavity 66 in the support piece 42, thereturn spring 88 can begin to pivot the locking member 76 clockwise inFIG. 21. One edge of the locking member 76 then begins to push againstthe upstanding post 82 on the shutter actuator 56 to begin to pivot theshutter actuator 56 clockwise in FIG. 21. Thus, in FIG. 21, the frontedge 118 of the shutter actuator 56 separates from the re-cockingprojection 114 on the metering/re-cocking member 104, and the frontguide pin 62 on the shutter actuator begins to be moved around the end136 of the island 64 in the cavity 66 in the support piece 42. Thereturn spring 88 continues to pivot the locking member 76 clockwise inFIG. 21. Consequently, the thumbwheel lock 84 begins to engage any oneof the peripheral teeth 86 on the film winding thumbwheel 30, and theactuating striker 68 begins to re-enter the slot 70 in the support piece42 (ahead of the tang 74 on the shutter blade 46) as shown in FIGS. 3and 4.

Finally, in FIG. 3, the actuator lock 80 re-engages the upstanding post82 on the shutter actuator 56 to prevent the shutter actuator from beingmoved substantially to the right in FIG. 3 via the spring 72. There-cocking projection 114 on the metering/re-cocking member 104 is keptspaced from the front edge 118 of the shutter actuator 56, whichprevents the tension spring 72 for the shutter actuator from having anyaffect on the metering/re-cocking member 104. This is important becausethe film sensing and metering pawls 106 and 108 of themetering/re-cocking member 104 are then in a pair of the filmperforations 110 and 112. If the film sensing and metering pawls 106 and108 were continuously subjected to the urging of the spring 72, inaddition to that of the spring 120, when the pawls are in a pair of thefilm perforations 110 and 112, the filmstrip 20 would be tensioned toomuch.

When the one-time-use camera 10 is dropped or jarred, the mechanicalshock may cause the shutter blade 46 to be slightly pivoted clockwise inFIG. 4 to separate from the blade stop end 54 of the light-interceptingrib 52. The closing spring 50 maintains the first closed end 128 of theslot 44 in the shutter blade against the pivot pin 40. Consequently, theshutter blade 46 is pivoted against the inclined blocking edge 124(closing the slight space 126 which is shown in FIG. 4) to prevent theshutter blade from being pivoted open to uncover the front aperture 26.Then, the closing spring 50 returns the shutter blade 46 to against theblade stop end 54 of the light-intercepting rib 52 and separates theshutter blade from the inclined blocking edge 124 (re-effecting theslight space 126 as shown in FIG. 4).

The invention has been described with reference to a preferredembodiment. However, it will be appreciated that variations andmodifications can be effected by a person of ordinary skill in the artwithout departing from the scope of the invention.

PARTS LIST

10. one-time-use camera

12. main body part

14. film take-up chamber

16. film cartridge

18. film supply chamber

20. filmstrip

22. unexposed film roll

24. exposure opening

26. front aperture

28. film frames

30. film winding thumbwheel

32. film winding direction

34. film take-up direction

36. taking lens

38. lens plate

39. lens retainer

40. pivot pin

42. support piece

44. slot

46. shutter blade

48. limit stop

50. closing spring

52. light-intercepting rib

54. blade stop end

56. shutter actuator

58. rear guide pin

60. slot

62. front guide pin

64. island

66. cavity

68. actuating striker

70. slot

72. tension spring

74. tang

76. locking member

78. pivot pin

80. actuator lock

82. upstanding post

84. thumbwheel lock

86. peripheral teeth

88. return spring

90. anti backup pawl

92. top piece

94. shutter release button

96. depending projection

98. upstanding projection

100. frame counter

102. viewfinder

104. metering/re-cocking member

106. film sensing pawl

108. film metering pawl

110. film perforation

112. film perforation

114. re-cocking projection

116. slot

118. front edge

120. tension spring

122. blocking device

124. inclined blocking edge

126. blocking range/clearance space

128. first closed end

130. second closed end

132. one end

134. opposite end

136. one end

138. front side

140. opposite end

142. follower

144. cam

146. nub

148. rear side

What is claimed is:
 1. A camera comprising a main body part with spacedfilm supply and film take-up chambers and an exposure opening locatedbetween said film supply and take-up chambers and configured forexposing an unexposed film frame, a metering pawl for engaging a filmperforation during exposure of the film frame at said exposure opening,and a film winding take-up for moving an exposed frame in a film take-updirection from said exposure opening to said film take-up chamber, ischaracterized in that:said metering pawl is supported to engage a filmperforation between said exposure opening and said film supply chamberduring exposure of a film frame at said exposure opening; and atensioning spring urges said metering pawl substantially opposite to thefilm take-up direction in order to tension a film frame at said exposureopening, to prevent frame shift during exposure of the film frame.
 2. Acamera as recited in claim 1, wherein said film winding take-up includesa film winding thumbwheel rotatable in a film winding direction to movean exposed frame in the film take-up direction and into a film cartridgein said take-up chamber, and an anti-backup pawl engages said filmwinding thumbwheel to prevent reverse rotation of the film windingthumbwheel when said tensioning spring urges said metering pawlsubstantially opposite to the film take-up direction in order to tensiona film frame at said exposure opening.
 3. A camera as recited in claim2, a thumbwheel lock engages said film winding thumbwheel to preventrotation of the film winding thumbwheel in the film winding directionand is movable out of engagement with the film winding thumbwheel, and ashutter release button is manually depressible to initiate exposure of afilm frame at said exposure opening and move said thumbwheel lock out ofengagement with said film winding thumbwheel.
 4. A camera as recited inclaim 3, wherein said anti-backup pawl engages said film windingthumbwheel when said thumbwheel lock is moved out of engagement withsaid film winding thumbwheel.
 5. A camera as recited in claim 1, whereina film sensing pawl is fixed with respect to said metering pawl and issupported to engage a film perforation when said metering pawl engages afilm perforation during exposure of a film frame at said exposureopening, and said tensioning spring urges said film sensing pawlsubstantially opposite to the film take-up direction in order to tensionthe film frame at said exposure opening.